1. Field of the Invention
This invention relates to gas/vapor cooled electromagnetic induction machines such as transformers, reactors, etc.
2. Description of the Prior Art
A gas/vapor cooled electromagnetic induction machine of the conventional type comprises an enclosed tank charged with a mixture of an amount of an electrically insulating gas non-condensable at operating temperatures and under operating gas pressures, for example, gaseous sulfur hexafluoride and an amount of a cooling gas condensable at the operating temperatures and under the operating gas pressures, for example, gaseous fluorocarbon. Within the enclosed tank there are disposed an iron core, along a longitudinal or vertical axis thereof, and a coil assembly consisting of a plurality of pancake coil sections wound at predetermined equal intervals around the iron core with the coil sections put between a pair of inner and outer electrically insulating cylinders. Also a dripping pan has been located above the iron core and the coil assembly within the enclosed tank and a condenser has been connected to the tank to condense the cooling gas into a condensate which is, in turn, collected on the lower portion of the tank.
When the electromagnetic induction machine is put in operation, an associated pump is actuated to supply the condensate collected on the lower tank portion to the dripping pan. The condensate supplied to the dripping pan drops on the coil sections and the iron core through a multitude of very small holes disposed at the bottom of the dripping pan. This contact with the iron core and the coil sections causes the condensate to increase in temperature and to be vaporized. At that time the iron core and the coil sections are deprived of a latent heat of vaporization of the condensate to be cooled. Thus the enclosed tank is filled with the mixture of the electrically insulating gas and the cooling gas now put in its gaseous phase. That mixture of gases enters into the condenser where only the cooling gas is condensed into its liquid phase to dissipate the latent heat of vaporization. The resulting condensate enters into the tank and is collected on the lower portion thereof. Then the process as described above is repeated to continuously cool the iron core and the coil sections.
In gas/vapor cooled electromagnetic induction machines such as described above, the condensate is dropped on the iron core and the coil sections but the drops of the condensate contact only the outer surface of the iron core and the upper surface and inner and outer lateral surfaces of the coil section. Thus the iron core and the coil sections have been unable to be uniformly cooled resulting in the disadvantages that the cooling efficiency is poor and the coil sections may locally increase in temperature.
Accordingly it is an object of the present invention to provide a new and improved gas/vapor cooled electromagnetic induction machine including means for efficiently cooling a coil assembly which generates a greater part of heat developed on the machine, and also including means for preventing the coil assembly from locally increasing in temperature.